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Yu C, Lad EM, Mathew R, Shiraki N, Littleton S, Chen Y, Hou J, Schlepckow K, Degan S, Chew L, Amason J, Kalnitsky J, Bowes Rickman C, Proia AD, Colonna M, Haass C, Saban DR. Microglia at sites of atrophy restrict the progression of retinal degeneration via galectin-3 and Trem2. J Exp Med 2024; 221:e20231011. [PMID: 38289348 PMCID: PMC10826045 DOI: 10.1084/jem.20231011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/11/2023] [Accepted: 01/12/2024] [Indexed: 02/01/2024] Open
Abstract
Outer retinal degenerations, including age-related macular degeneration (AMD), are characterized by photoreceptor and retinal pigment epithelium (RPE) atrophy. In these blinding diseases, macrophages accumulate at atrophic sites, but their ontogeny and niche specialization remain poorly understood, especially in humans. We uncovered a unique profile of microglia, marked by galectin-3 upregulation, at atrophic sites in mouse models of retinal degeneration and human AMD. In disease models, conditional deletion of galectin-3 in microglia led to phagocytosis defects and consequent augmented photoreceptor death, RPE damage, and vision loss, indicating protective roles. Mechanistically, Trem2 signaling orchestrated microglial migration to atrophic sites and induced galectin-3 expression. Moreover, pharmacologic Trem2 agonization led to heightened protection but in a galectin-3-dependent manner. In elderly human subjects, we identified this highly conserved microglial population that expressed galectin-3 and Trem2. This population was significantly enriched in the macular RPE-choroid of AMD subjects. Collectively, our findings reveal a neuroprotective population of microglia and a potential therapeutic target for mitigating retinal degeneration.
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Affiliation(s)
- Chen Yu
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Eleonora M. Lad
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Rose Mathew
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Nobuhiko Shiraki
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Sejiro Littleton
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
- Department of Immunology, Duke University, Durham, NC, USA
| | - Yun Chen
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jinchao Hou
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Kai Schlepckow
- German Center for Neurodegenerative Diseases Munich, Munich, Germany
| | - Simone Degan
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Lindsey Chew
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Joshua Amason
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Joan Kalnitsky
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - Alan D. Proia
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC, USA
- Department of Pathology, Campbell University Jerry M. Wallace School of Osteopathic Medicine, Lillington, NC, USA
| | - Marco Colonna
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - Christian Haass
- German Center for Neurodegenerative Diseases Munich, Munich, Germany
- Chair of Metabolic Biochemistry, Faculty of Medicine, Biomedical Center, Ludwig-Maximilians-Universität München, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Daniel R. Saban
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
- Department of Immunology, Duke University, Durham, NC, USA
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2
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Zhao Q, Lai K. Role of immune inflammation regulated by macrophage in the pathogenesis of age-related macular degeneration. Exp Eye Res 2024; 239:109770. [PMID: 38145794 DOI: 10.1016/j.exer.2023.109770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/05/2023] [Accepted: 12/20/2023] [Indexed: 12/27/2023]
Abstract
Age-related macular degeneration (AMD) can lead to irreversible impairment of visual function, and the number of patients with AMD has been increasing globally. The immunoinflammatory theory is an important pathogenic mechanism of AMD, with macrophages serving as the primary inflammatory infiltrating cells in AMD lesions. Its powerful immunoinflammatory regulatory function has attracted considerable attention. Herein, we provide an overview of the involvement of macrophage-regulated immunoinflammation in different stages of AMD. Additionally, we summarize novel therapeutic approaches for AMD, focusing on targeting macrophages, such as macrophage/microglia modulators, reduction of macrophage aggregation in the subretinal space, modulation of macrophage effector function, macrophage phenotypic alterations, and novel biomimetic nanocomposites development based on macrophage-associated functional properties. We aimed to provide a basis and reference for the further exploration of AMD pathogenesis, developmental influences, and new therapeutic approaches.
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Affiliation(s)
- Qin Zhao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, No.7 Jinsui Road, Guangzhou, 510060, China
| | - Kunbei Lai
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, No.7 Jinsui Road, Guangzhou, 510060, China.
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3
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Donato L, Mordà D, Scimone C, Alibrandi S, D’Angelo R, Sidoti A. Bridging Retinal and Cerebral Neurodegeneration: A Focus on Crosslinks between Alzheimer-Perusini's Disease and Retinal Dystrophies. Biomedicines 2023; 11:3258. [PMID: 38137479 PMCID: PMC10741418 DOI: 10.3390/biomedicines11123258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/02/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
In the early stages of Alzheimer-Perusini's disease (AD), individuals often experience vision-related issues such as color vision impairment, reduced contrast sensitivity, and visual acuity problems. As the disease progresses, there is a connection with glaucoma and age-related macular degeneration (AMD) leading to retinal cell death. The retina's involvement suggests a link with the hippocampus, where most AD forms start. A thinning of the retinal nerve fiber layer (RNFL) due to the loss of retinal ganglion cells (RGCs) is seen as a potential AD diagnostic marker using electroretinography (ERG) and optical coherence tomography (OCT). Amyloid beta fragments (Aβ), found in the eye's vitreous and aqueous humor, are also present in the cerebrospinal fluid (CSF) and accumulate in the retina. Aβ is known to cause tau hyperphosphorylation, leading to its buildup in various retinal layers. However, diseases like AD are now seen as mixed proteinopathies, with deposits of the prion protein (PrP) and α-synuclein found in affected brains and retinas. Glial cells, especially microglial cells, play a crucial role in these diseases, maintaining immunoproteostasis. Studies have shown similarities between retinal and brain microglia in terms of transcription factor expression and morphotypes. All these findings constitute a good start to achieving better comprehension of neurodegeneration in both the eye and the brain. New insights will be able to bring the scientific community closer to specific disease-modifying therapies.
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Affiliation(s)
- Luigi Donato
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, 98122 Messina, Italy; (L.D.); (C.S.); (R.D.); (A.S.)
- Department of Biomolecular Strategies, Genetics, Cutting-Edge Therapies, Euro-Mediterranean Institute of Science and Technology (I.E.ME.S.T.), 90139 Palermo, Italy;
| | - Domenico Mordà
- Department of Biomolecular Strategies, Genetics, Cutting-Edge Therapies, Euro-Mediterranean Institute of Science and Technology (I.E.ME.S.T.), 90139 Palermo, Italy;
- Department of Veterinary Sciences, University of Messina, 98122 Messina, Italy
| | - Concetta Scimone
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, 98122 Messina, Italy; (L.D.); (C.S.); (R.D.); (A.S.)
- Department of Biomolecular Strategies, Genetics, Cutting-Edge Therapies, Euro-Mediterranean Institute of Science and Technology (I.E.ME.S.T.), 90139 Palermo, Italy;
| | - Simona Alibrandi
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, 98122 Messina, Italy; (L.D.); (C.S.); (R.D.); (A.S.)
- Department of Biomolecular Strategies, Genetics, Cutting-Edge Therapies, Euro-Mediterranean Institute of Science and Technology (I.E.ME.S.T.), 90139 Palermo, Italy;
| | - Rosalia D’Angelo
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, 98122 Messina, Italy; (L.D.); (C.S.); (R.D.); (A.S.)
| | - Antonina Sidoti
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, 98122 Messina, Italy; (L.D.); (C.S.); (R.D.); (A.S.)
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4
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Ruiz-Pastor MJ, Sánchez-Sáez X, Kutsyr O, Albertos-Arranz H, Sánchez-Castillo C, Ortuño-Lizarán I, Martínez-Gil N, Vidal-Gil L, Méndez L, Sánchez-Martín M, Maneu V, Lax P, Cuenca N. Prph2 knock-in mice recapitulate human central areolar choroidal dystrophy retinal degeneration and exhibit aberrant synaptic remodeling and microglial activation. Cell Death Dis 2023; 14:711. [PMID: 37914688 PMCID: PMC10620171 DOI: 10.1038/s41419-023-06243-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/16/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023]
Abstract
Central areolar choroidal dystrophy is an inherited disorder characterized by progressive choriocapillaris atrophy and retinal degeneration and is usually associated with mutations in the PRPH2 gene. We aimed to generate and characterize a mouse model with the p.Arg195Leu mutation previously described in patients. Heterozygous (Prph2WT/KI) and homozygous (Prph2KI/KI) mice were generated using the CRISPR/Cas9 system to introduce the p.Arg195Leu mutation. Retinal function was assessed by electroretinography and optomotor tests at 1, 3, 6, 9, 12, and 20 months of age. The structural integrity of the retinas was evaluated at the same ages using optical coherence tomography. Immunofluorescence and transmission electron microscopy images of the retina were also analyzed. Genetic sequencing confirmed that both Prph2WT/KI and Prph2KI/KI mice presented the p.Arg195Leu mutation. A progressive loss of retinal function was found in both mutant groups, with significantly reduced visual acuity from 3 months of age in Prph2KI/KI mice and from 6 months of age in Prph2WT/KI mice. Decreased amplitudes in the electroretinography responses were observed from 1 month of age in Prph2KI/KI mice and from 6 months of age in Prph2WT/KI mice. Morphological analysis of the retinas correlated with functional findings, showing a progressive decrease in retinal thickness of mutant mice, with earlier and more severe changes in the homozygous mutant mice. We corroborated the alteration of the outer segment structure, and we found changes in the synaptic connectivity in the outer plexiform layer as well as gliosis and signs of microglial activation. The new Prph2WT/KI and Prph2KI/KI murine models show a pattern of retinal degeneration similar to that described in human patients with central areolar choroidal dystrophy and appear to be good models to study the mechanisms involved in the onset and progression of the disease, as well as to test the efficacy of new therapeutic strategies.
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Affiliation(s)
| | - Xavier Sánchez-Sáez
- Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain
| | - Oksana Kutsyr
- Optics, Pharmacology, and Anatomy, University of Alicante, Alicante, Spain
| | | | | | | | | | - Lorena Vidal-Gil
- Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain
| | - Lucía Méndez
- Transgenic Facility and Department of Medicine, University of Salamanca, Salamanca, Spain
| | - Manuel Sánchez-Martín
- Transgenic Facility and Department of Medicine, University of Salamanca, Salamanca, Spain
- Institute for Biomedical Research of Salamanca (IBSAL), Salamanca, Spain
| | - Victoria Maneu
- Optics, Pharmacology, and Anatomy, University of Alicante, Alicante, Spain
- Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain
| | - Pedro Lax
- Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain.
- Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain.
| | - Nicolás Cuenca
- Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain.
- Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain.
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5
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Yu C, Lad EM, Mathew R, Littleton S, Chen Y, Schlepckow K, Degan S, Chew L, Amason J, Kalnitsky J, Rickman CB, Proia AD, Colonna M, Haass C, Saban DR. Microglia at Sites of Atrophy Restrict the Progression of Retinal Degeneration via Galectin-3 and Trem2 Interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.19.549403. [PMID: 37502831 PMCID: PMC10370087 DOI: 10.1101/2023.07.19.549403] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Degenerative diseases of the outer retina, including age-related macular degeneration (AMD), are characterized by atrophy of photoreceptors and retinal pigment epithelium (RPE). In these blinding diseases, macrophages are known to accumulate ectopically at sites of atrophy, but their ontogeny and functional specialization within this atrophic niche remain poorly understood, especially in the human context. Here, we uncovered a transcriptionally unique profile of microglia, marked by galectin-3 upregulation, at atrophic sites in mouse models of retinal degeneration and in human AMD. Using disease models, we found that conditional deletion of galectin-3 in microglia led to defects in phagocytosis and consequent augmented photoreceptor death, RPE damage and vision loss, suggestive of a protective role. Mechanistically, Trem2 signaling orchestrated the migration of microglial cells to sites of atrophy, and there, induced galectin-3 expression. Moreover, pharmacologic Trem2 agonization led to heightened protection, but only in a galectin-3-dependent manner, further signifying the functional interdependence of these two molecules. Likewise in elderly human subjects, we identified a highly conserved population of microglia at the transcriptomic, protein and spatial levels, and this population was enriched in the macular region of postmortem AMD subjects. Collectively, our findings reveal an atrophy-associated specialization of microglia that restricts the progression of retinal degeneration in mice and further suggest that these protective microglia are conserved in AMD.
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Affiliation(s)
- Chen Yu
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Eleonora M Lad
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Rose Mathew
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Sejiro Littleton
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
- Department of Immunology, Duke University; Durham, NC 27710, USA
| | - Yun Chen
- Department of Pathology and Immunology, Washington University School of Medicine; St. Louis, MO 63110, USA
- Department of Neurology, Washington University School of Medicine; St. Louis, MO 63110, USA
| | - Kai Schlepckow
- German Center for Neurodegenerative Diseases (DZNE) Munich; 81377 Munich, Germany
| | - Simone Degan
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Lindsey Chew
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Joshua Amason
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Joan Kalnitsky
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
- Department of Cell Biology, Duke University; Durham, NC 27710, USA
| | - Alan D Proia
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
- Department of Pathology, Duke University School of Medicine; Durham, NC 27710, USA
- Department of Pathology, Campbell University Jerry M. Wallace School of Osteopathic Medicine, Lillington, NC 27546, USA
| | - Marco Colonna
- Department of Pathology and Immunology, Washington University School of Medicine; St. Louis, MO 63110, USA
| | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE) Munich; 81377 Munich, Germany
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München; 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy); 81377 Munich, Germany
| | - Daniel R Saban
- Department of Ophthalmology, Duke University School of Medicine; Durham, NC 27710, USA
- Department of Immunology, Duke University; Durham, NC 27710, USA
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Goyal M, Bordt AS, Neitz J, Marshak DW. Trogocytosis of neurons and glial cells by microglia in a healthy adult macaque retina. Sci Rep 2023; 13:633. [PMID: 36635325 PMCID: PMC9837165 DOI: 10.1038/s41598-023-27453-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 01/02/2023] [Indexed: 01/13/2023] Open
Abstract
Microglial cells are the primary resident immune cells in the retina. In healthy adults, they are ramified; that is, they have extensive processes that move continually. In adult retinas, microglia maintain the normal structure and function of neurons and other glial cells, but the mechanism underlying this process is not well-understood. In the mouse hippocampus, microglia engulf small pieces of axons and presynaptic terminals via a process called trogocytosis. Here we report that microglia in the adult macaque retina also engulf pieces of neurons and glial cells, but not at sites of synapses. We analyzed microglia in a volume of serial, ultrathin sections of central macaque retina in which many neurons that ramify in the inner plexiform layer (IPL) had been reconstructed previously. We surveyed the IPL and identified the somas of microglia by their small size and scant cytoplasm. We then reconstructed the microglia and studied their interactions with other cells. We found that ramified microglia frequently ingested small pieces of each major type of inner retinal neuron and Müller glial cells via trogocytosis. There were a few instances where the interactions took place near synapses, but the synapses, themselves, were never engulfed. If trogocytosis by retinal microglia plays a role in synaptic remodeling, it was not apparent from the ultrastructure. Instead, we propose that trogocytosis enables these microglia to present antigens derived from normal inner retinal cells and, when activated, they would promote antigen-specific tolerance.
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Affiliation(s)
- Megan Goyal
- Department of Neurobiology and Anatomy, McGovern Medical School, Houston, TX, USA
| | - Andrea S Bordt
- Department of Neurobiology and Anatomy, McGovern Medical School, Houston, TX, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Jay Neitz
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - David W Marshak
- Department of Neurobiology and Anatomy, McGovern Medical School, Houston, TX, USA.
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McPherson SW, Heuss ND, Abedin M, Roehrich H, Pierson MJ, Gregerson DS. Parabiosis reveals the correlation between the recruitment of circulating antigen presenting cells to the retina and the induction of spontaneous autoimmune uveoretinitis. J Neuroinflammation 2022; 19:295. [PMID: 36494807 PMCID: PMC9733026 DOI: 10.1186/s12974-022-02660-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Characterizing immune cells and conditions that govern their recruitment and function in autoimmune diseases of the nervous system or in neurodegenerative processes is an area of active investigation. We sought to analyze the origin of antigen presenting cells associated with the induction of retinal autoimmunity using a system that relies on spontaneous autoimmunity, thus avoiding uncertainties associated with immunization with adjuvants at remotes sites or adoptive transfer of in vitro activated T cells. METHODS R161H mice (B10.RIII background), which spontaneously and rapidly develop severe spontaneous autoimmune uveoretinitis (SAU), were crossed to CD11cDTR/GFP mice (B6/J) allowing us to track the recruitment to and/or expansion within the retina of activated, antigen presenting cells (GFPhi cells) in R161H+/- × CD11cDTR/GFP F1 mice relative to the course of SAU. Parabiosis between R161H+/- × CD11cDTR/GFP F1 mice and B10.RIII × B6/J F1 (wild-type recipient) mice was done to explore the origin and phenotype of antigen presenting cells crucial for the induction of autoimmunity. Analysis was done by retinal imaging, flow cytometry, and histology. RESULTS Onset of SAU in R161H+/- × CD11cDTR/GFP F1 mice was delayed relative to B10.RIII-R161H+/- mice revealing a disease prophase prior to frank autoimmunity that was characterized by expansion of GFPhi cells within the retina prior to any clinical or histological evidence of autoimmunity. Parabiosis between mice carrying the R161H and CD11cDTR/GFP transgenes and transgene negative recipients showed that recruitment of circulating GFPhi cells into retinas was highly correlative with the occurrence of SAU. CONCLUSIONS Our results here contrast with our previous findings showing that retinal antigen presenting cells expanding in response to either sterile mechanical injury or neurodegeneration were derived from myeloid cells within the retina or optic nerve, thus highlighting a unique facet of retinal autoimmunity.
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Affiliation(s)
- Scott W. McPherson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, Lions Research Building, Room 482A, Minneapolis, MN 55455 USA
| | - Neal D. Heuss
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, Lions Research Building, Room 482A, Minneapolis, MN 55455 USA
| | - Md. Abedin
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, Lions Research Building, Room 482A, Minneapolis, MN 55455 USA
| | - Heidi Roehrich
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, Lions Research Building, Room 482A, Minneapolis, MN 55455 USA
| | - Mark J. Pierson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, Lions Research Building, Room 482A, Minneapolis, MN 55455 USA
| | - Dale S. Gregerson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, Lions Research Building, Room 482A, Minneapolis, MN 55455 USA
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8
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Murenu E, Gerhardt MJ, Biel M, Michalakis S. More than meets the eye: The role of microglia in healthy and diseased retina. Front Immunol 2022; 13:1006897. [PMID: 36524119 PMCID: PMC9745050 DOI: 10.3389/fimmu.2022.1006897] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/11/2022] [Indexed: 11/30/2022] Open
Abstract
Microglia are the main resident immune cells of the nervous system and as such they are involved in multiple roles ranging from tissue homeostasis to response to insults and circuit refinement. While most knowledge about microglia comes from brain studies, some mechanisms have been confirmed for microglia cells in the retina, the light-sensing compartment of the eye responsible for initial processing of visual information. However, several key pieces of this puzzle are still unaccounted for, as the characterization of retinal microglia has long been hindered by the reduced population size within the retina as well as the previous lack of technologies enabling single-cell analyses. Accumulating evidence indicates that the same cell type may harbor a high degree of transcriptional, morphological and functional differences depending on its location within the central nervous system. Thus, studying the roles and signatures adopted specifically by microglia in the retina has become increasingly important. Here, we review the current understanding of retinal microglia cells in physiology and in disease, with particular emphasis on newly discovered mechanisms and future research directions.
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Affiliation(s)
- Elisa Murenu
- Department of Ophthalmology, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany,*Correspondence: Elisa Murenu, ; ; Stylianos Michalakis,
| | | | - Martin Biel
- Department of Pharmacy, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stylianos Michalakis
- Department of Ophthalmology, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany,*Correspondence: Elisa Murenu, ; ; Stylianos Michalakis,
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9
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Gramlich OW, Godwin CR, Heuss ND, Gregerson DS, Kuehn MH. T and B Lymphocyte Deficiency in Rag1-/- Mice Reduces Retinal Ganglion Cell Loss in Experimental Glaucoma. Invest Ophthalmol Vis Sci 2021; 61:18. [PMID: 33320171 PMCID: PMC7745626 DOI: 10.1167/iovs.61.14.18] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose We previously demonstrated that passive transfer of lymphocytes from glaucomatous mice induces retinal ganglion cell (RGC) damage in recipient animals, suggesting a role for immune responses in the multifactorial pathophysiology of glaucoma. Here we evaluate whether absence of an adaptive immune response reduces RGC loss in glaucoma. Methods Elevated intraocular pressure (IOP) was induced in one eye of C57BL/6J (B6) or T- and B-cell–deficient Rag1−/− knockout mice. After 16 weeks RGC density was determined in both the induced and the normotensive contralateral eyes. Data were compared to mice having received injections of “empty” vector (controls). The number of extravascular CD3+ cells in the retinas was determined using FACS. Results Retinas of eyes with elevated IOP contain significantly more extravasated CD3+ cells than control retinas (46.0 vs. 27.1, P = 0.025). After 16 weeks of elevated IOP the average RGC density in B6 mice decreased by 20.7% (P = 1.9 × 10−4). In contrast, RGC loss in Rag1−/− eyes with elevated IOP was significantly lower (10.3%, P = 0.006 vs. B6). RGC loss was also observed in the contralateral eyes of B6 mice, despite the absence of elevated IOP in those eyes (10.1%; P = 0.008). In RAG1−/− loss in the contralateral eyes was minimal (3.1%) and significantly below that detected in B6 (P = 0.02). Conclusions Our findings demonstrate that T Rag1−/− mice are significantly protected from glaucomatous RGC loss. In this model, lymphocyte activity contributes to approximately half of all RGC loss in eyes with elevated IOP and to essentially all loss observed in normotensive contralateral eyes.
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Affiliation(s)
- Oliver W Gramlich
- University of Iowa, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Health Care System, Iowa City, Iowa, United States
| | - Cheyanne R Godwin
- University of Iowa, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Health Care System, Iowa City, Iowa, United States
| | - Neal D Heuss
- University of Minnesota, Department of Ophthalmology and Visual Neurosciences, Minneapolis, Minnesota, United States
| | - Dale S Gregerson
- University of Minnesota, Department of Ophthalmology and Visual Neurosciences, Minneapolis, Minnesota, United States
| | - Markus H Kuehn
- University of Iowa, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Health Care System, Iowa City, Iowa, United States
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Kutsyr O, Sánchez-Sáez X, Martínez-Gil N, de Juan E, Lax P, Maneu V, Cuenca N. Gradual Increase in Environmental Light Intensity Induces Oxidative Stress and Inflammation and Accelerates Retinal Neurodegeneration. Invest Ophthalmol Vis Sci 2021; 61:1. [PMID: 32744596 PMCID: PMC7441298 DOI: 10.1167/iovs.61.10.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose Retinitis pigmentosa (RP) is a blinding neurodegenerative disease of the retina that can be affected by many factors. The present study aimed to analyze the effect of different environmental light intensities in rd10 mice retina. Methods C57BL/6J and rd10 mice were bred and housed under three different environmental light intensities: scotopic (5 lux), mesopic (50 lux), and photopic (300 lux). Visual function was studied using electroretinography and optomotor testing. The structural and morphological integrity of the retinas was evaluated by optical coherence tomography imaging and immunohistochemistry. Additionally, inflammatory processes and oxidative stress markers were analyzed by flow cytometry and western blotting. Results When the environmental light intensity was higher, retinal function decreased in rd10 mice and was accompanied by light-dependent photoreceptor loss, followed by morphological alterations, and synaptic connectivity loss. Moreover, light-dependent retinal degeneration was accompanied by an increased number of inflammatory cells, which became more activated and phagocytic, and by an exacerbated reactive gliosis. Furthermore, light-dependent increment in oxidative stress markers in rd10 mice retina pointed to a possible mechanism for light-induced photoreceptor degeneration. Conclusions An increase in rd10 mice housing light intensity accelerates retinal degeneration, activating cell death, oxidative stress pathways, and inflammatory cells. Lighting intensity is a key factor in the progression of retinal degeneration, and standardized lighting conditions are advisable for proper analysis and interpretation of experimental results from RP animal models, and specifically from rd10 mice. Also, it can be hypothesized that light protection could be an option to slow down retinal degeneration in some cases of RP.
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Increased Neuroprotective Microglia and Photoreceptor Survival in the Retina from a Peptide Inhibitor of Myeloid Differentiation Factor 88 (MyD88). J Mol Neurosci 2020; 70:968-980. [PMID: 32072483 DOI: 10.1007/s12031-020-01503-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 02/05/2020] [Indexed: 01/14/2023]
Abstract
Myeloid differentiation factor 88 (MyD88) is an adaptor protein for the Toll-like receptor (TLR) and interleukin 1 receptor (IL-1R) families of innate immunity receptors that mediate inflammatory responses to cellular injury. TLR/IL1R/MyD88 signaling is known to contribute to retinal degeneration, although how MyD88 regulates neuronal survival, and the effect of MyD88 on the inflammatory environment in the retina, is mostly unknown. In this study, we tested the hypothesis that blocking MyD88-mediated signaling early in retinal degeneration promotes transition of microglia towards a neuroprotective anti-inflammatory phenotype, resulting in enhanced photoreceptor survival. We also tested whether systemic delivery of a pharmacologic MyD88 inhibitor has therapeutic potential. The rd10 mouse model of retinal degeneration was injected intraperitoneally with increasing doses of a MyD88 blocking peptide or control peptide early in degeneration, and inflammatory responses and photoreceptor survival were measured at specific time points using flow cytometry, cytokine profiling, and electroretinograms. Our results demonstrated that rd10 mice injected with a low dose of MyD88 inhibitor peptide showed increased rod photoreceptor function and reduced apoptosis compared with control peptide and uninjected mice. MyD88 inhibition also resulted in fewer microglia/macrophage cells in the photoreceptor layer whereas total peripheral and retinal macrophage were not changed. Furthermore, increased number of cells expressing the Arg1 marker of neuroprotective microglia in the photoreceptor layer and higher MCP-1 and anti-inflammatory cytokine IL-27 were associated with photoreceptor survival. Therefore, these data suggest that the MyD88 inhibitor modified the retina environment to become less inflammatory, leading to improved photoreceptor function and survival.
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Abstract
Microglia are increasingly shown to be key players in neuron development and synapse connectivity. However, the underlying mechanisms by which microglia regulate neuron function remain poorly understood in part because such analysis is challenging in the brain where neurons and synapses are intermingled and connectivity is only beginning to be mapped. Here, we discuss the features and function of microglia in the ordered mammalian retina where the laminar organization of neurons and synapses facilitates such molecular studies. We discuss microglia origins and consider the evidence for molecularly distinct microglia subpopulations and their potential for differential roles with a particular focus on the early stages of retina development. We then review the models and methods used for the study of these cells and discuss emerging data that link retina microglia to the genesis and survival of particular retina cell subtypes. We also highlight potential roles for microglia in shaping the development and organization of the vasculature and discuss cellular and molecular mechanisms involved in this process. Such insights may help resolve the mechanisms by which retinal microglia impact visual function and help guide studies of related features in brain development and disease.
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Affiliation(s)
- Fenge Li
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danye Jiang
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Melanie A Samuel
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, 77030, USA.
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McPherson SW, Heuss ND, Lehmann U, Roehrich H, Abedin M, Gregerson DS. The retinal environment induces microglia-like properties in recruited myeloid cells. J Neuroinflammation 2019; 16:151. [PMID: 31325968 PMCID: PMC6642741 DOI: 10.1186/s12974-019-1546-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 07/11/2019] [Indexed: 12/31/2022] Open
Abstract
Background Microglia are essential to the development of the CNS and its homeostasis. Our prior findings suggested a niche model to describe the behaviors of retinal microglia. Here, we ask whether new myeloid cells recruited to the retina are constrained to resemble endogenous microglia morphologically and functionally. Methods Use of CD11cDTR/GFP transgenic mouse allowed identification of two niches of retinal microglia distinguished by being GFPlo or GFPhi. We also used transgenic mice in which CX3CR1+ cells expressed YFP and were depletable following tamoxifen-induced expression of diphtheria toxin subunit A. We employed several ablation and injury stimulation protocols to examine the origin and fate of myeloid cells repopulating the retina. Analysis of retinal myeloid cells was done by microscopy, flow cytometry, and qRT-PCR. Results We found that the origin of new GFPhi and GFPlo myeloid cells in the retina of CD11cDTR/GFP mice, whether recruited or local, depended on the ablation and stimulation protocols. Regardless of origin, new GFPlo and GFPhi retinal myeloid cells were CD45medCD11b+Ly6G−Ly6CloIba1+F4/80+, similar to endogenous microglia. Following tamoxifen-induced diphtheria toxin ablation, myeloid cell repopulation differed in the retina compared to the brain and optic nerve. Stimulation of replacement GFPhi cells was substantially attenuated in repopulating retinas after tamoxifen-induced diphtheria toxin ablation compared to control or radiation-ablated mice. In radiation bone marrow chimeric mice, replacement GFPhi myeloid cells from the circulation were slow to repopulate the retina unless stimulated by an optic nerve crush injury. However, once stimulated, recruited GFPhi cells were found to concentrate on injured retinal ganglion cells and were morphologically similar to GFPhi cells in non-ablated control CD11cDTR/GFP mice. Conclusions The results support the idea that GFPhi cells in the CD11cDTR/GFP mouse, whether recruited or from resident microglia, mark a unique niche of activated retinal myeloid cells. We conclude that the retinal environment has a potent influence on the function, morphology, and proliferative capacity of new myeloid cells regardless of their origin, compelling them to be equivalent to the endogenous microglia. Electronic supplementary material The online version of this article (10.1186/s12974-019-1546-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Scott W McPherson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, LRB Room 314, Minneapolis, MN, 55455, USA.
| | - Neal D Heuss
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, LRB Room 314, Minneapolis, MN, 55455, USA
| | - Ute Lehmann
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, LRB Room 314, Minneapolis, MN, 55455, USA
| | - Heidi Roehrich
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, LRB Room 314, Minneapolis, MN, 55455, USA
| | - Md Abedin
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, LRB Room 314, Minneapolis, MN, 55455, USA
| | - Dale S Gregerson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 2001 6th Street SE, LRB Room 314, Minneapolis, MN, 55455, USA
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McMenamin PG, Saban DR, Dando SJ. Immune cells in the retina and choroid: Two different tissue environments that require different defenses and surveillance. Prog Retin Eye Res 2018; 70:85-98. [PMID: 30552975 DOI: 10.1016/j.preteyeres.2018.12.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 12/03/2018] [Accepted: 12/11/2018] [Indexed: 01/04/2023]
Abstract
In the eye immune defenses must take place in a plethora of differing microenvironments ranging from the corneal and conjunctival epithelia facing the external environment to the pigmented connective tissue of the uveal tract containing smooth muscle, blood vessels and peripheral nerves to the innermost and highly protected neural retina. The extravascular environment of the neural retina, like the brain parenchyma, is stringently controlled to maintain conditions required for neural transmission. The unique physiological nature of the neural retina can be attributed to the blood retinal barriers (BRB) of the retinal vasculature and the retinal pigment epithelium, which both tightly regulate the transport of small molecules and restrict passage of cells and macromolecules from the circulation into the retina in a similar fashion to the blood brain barrier (BBB). The extracellular environment of the neural retina differs markedly from that of the highly vascular, loose connective tissue of the choroid, which lies outside the BRB. The choroid hosts a variety of immune cell types, including macrophages, dendritic cells (DCs) and mast cells. This is in marked contrast to the neural parenchyma of the retina, which is populated almost solely by microglia. This review will describe the current understanding of the distribution, phenotype and physiological role of ocular immune cells behind or inside the blood-retinal barriers and those in closely juxtaposed tissues outside the barrier. The nature and function of these immune cells can profoundly influence retinal homeostasis and lead to disordered immune function that can lead to vision loss.
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Affiliation(s)
- Paul G McMenamin
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
| | - Daniel R Saban
- Department of Ophthalmology, Department of Immunology, Duke University School of Medicine, Durham, NC, USA
| | - Samantha J Dando
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
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Heuss ND, Pierson MJ, Roehrich H, McPherson SW, Gram AL, Li L, Gregerson DS. Optic nerve as a source of activated retinal microglia post-injury. Acta Neuropathol Commun 2018; 6:66. [PMID: 30037353 PMCID: PMC6055350 DOI: 10.1186/s40478-018-0571-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 07/15/2018] [Indexed: 12/27/2022] Open
Abstract
Using mice expressing green fluorescent protein (GFP) from a transgenic CD11c promoter we found that a controlled optic nerve crush (ONC) injury attracted GFPhi retinal myeloid cells to the dying retinal ganglion cells and their axons. However, the origin of these retinal myeloid cells was uncertain. In this study we use transgenic mice in conjunction with ONC, partial and full optic nerve transection (ONT), and parabiosis to determine the origin of injury induced retinal myeloid cells. Analysis of parabiotic mice and fate mapping showed that responding retinal myeloid cells were not derived from circulating macrophages and that GFPhi myeloid cells could be derived from GFPlo microglia. Comparison of optic nerve to retina following an ONC showed a much greater concentration of GFPhi cells and GFPlo microglia in the optic nerve. Optic nerve injury also induced Ki67+ cells in the optic nerve but not in the retina. Comparison of the retinal myeloid cell response after full versus partial ONT revealed fewer GFPhi cells and GFPlo microglia in the retina following a full ONT despite it being a more severe injury, suggesting that full transection of the optic nerve can block the migration of responding myeloid cells to the retina. Our results suggest that the optic nerve can be a reservoir for activated microglia and other retinal myeloid cells in the retina following optic nerve injury.
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Saban DR. New concepts in macrophage ontogeny in the adult neural retina. Cell Immunol 2018; 330:79-85. [PMID: 29703455 DOI: 10.1016/j.cellimm.2018.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 04/20/2018] [Accepted: 04/20/2018] [Indexed: 12/16/2022]
Abstract
The number of neurons dedicated to vision itself is thought to be greater than the sum of the four other senses combined. Yet, little attention has been payed to the retina as compared to elsewhere in the central nervous system with respect to microglia, the macrophages of the neural parenchyma. Indeed, major advancements in the understanding of microglial ontogeny and maintenance in brain and spinal cord are now widely appreciated, whereas less notice has been given to the neural retina in this regard. The current Review covers topical concepts on adult microglia and perivascular macrophage ontogenies in the steady state retina, as well as parallels made with these macrophages in other areas of the central nervous system. The subject of recruited monocytes and their descendant monocyte-derived macrophages in degenerative diseases of the retina is also integrated into this Review. Key experiments that have led to the theories covered are highlighted throughout, as are the knowledge gaps that remain unresolved.
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Affiliation(s)
- Daniel R Saban
- Duke University School of Medicine, Department of Ophthalmology, Durham, NC, USA; Duke University School of Medicine, Department of Immunology, Durham, NC, USA.
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